Module completion 

Word collection and prefix matching for autocomplete.

Functions

char_to_byte

Converts the character index char_index into a byte offset into text, returning the text length when the index is past the end.

collect_words

Collects the unique words of text (length ≥ 3) with their occurrence count, sorted by count descending and then alphabetically.

current_prefix

Returns the run of word characters ending immediately before cursor, where cursor is a character index into text.

current_word

Returns the character-index range of the word containing cursor, scanning both backward and forward from it with is_word_char.

is_word_char

Returns whether character counts as part of a word (alphanumeric or _).

matches

Returns the words starting with prefix and their occurrence count.